Rocket

The rocket travels a distance:
during the time when it accelerates. The rocket velocity at the end
of this time is
The second half of its path can be found by writing the kinematic
equations you have learned, and plugging in
and
(a) The highest point of the path is when
so
=>
=>
We then use this time to help find how high the rocket goes up.
(b) The easiest way to find the total time of flight is to solve the
equation for
at the time when the rocket has returned to the ground:
This is a quadratic equation and has TWO solutions for t. But one
is negative and so physically impossible. The other is
This is the free fall part of the problem. To find the total time
we need to add to this also the 60 seconds when there was acceleration.
The total time is then 330 seconds.